1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) panel. More particularly, the present invention relates to a LCD panel with a light-shielding pattern disposed at the periphery of the panel.
2. Description of Related Art
The rapid advancement in semiconductor devices and display apparatuses brings the rapid advancement of a multimedia society. As to display panels, thin film transistor liquid crystal display (TFT LCD) has become the leading product in display market due to its characteristics such as high image quality, high space efficiency, low power consumption, and no radiation.
Generally speaking, a TFT LCD is composed of a TFT array substrate, a color filter substrate, and a liquid crystal layer sandwiched between the two substrates. The surface of the TFT array substrate has a plurality of pixel regions arranged as an array, and each of the pixel regions contains a TFT and a pixel electrode for controlling the rotations of the liquid crystal molecules in the pixel region so that each of the pixels can produce grey scale of different color.
LCD panels can be categorized into vacuum injection and one drop fill (ODF) according to the injection of liquid crystal molecules. According to vacuum injection, first a TFT array substrate and a color filter substrate are assembled and an opening is left for injecting liquid crystal; the chamber of the liquid crystal injection apparatus and the space between the two substrates is then vacuumed and the liquid crystal injection opening is immersed in the liquid crystal, release the vacuum of the chamber, so that the liquid crystal is injected into the space between the two substrates by the pressure difference. According to ODF, first a pattern of sealant is dispensed on the periphery of the TFT array substrate and the liquid crystal are dropped into the display region of the TFT array substrate; after that, the TFT array substrate and the color filter substrate are assembled in a vacuum chamber; finally, the sealant is radiated and hardened by a ultraviolet. Compared to vacuum injection, ODF can reduce the time for injecting liquid crystal and the quantity of the liquid crystal; thus, presently ODF is generally used for injecting liquid crystal in large-size LCD panels.
FIG. 1A is partial cross-sectional view of a conventional liquid crystal display (LCD) panel fabricated through one drop fill (ODF). Referring to FIG. 1A, the LCD panel 100 includes a TFT array substrate 110, a color filter substrate 120, and a liquid crystal layer 130. The color filter substrate 120 is disposed above the TFT array substrate 110 in parallel, and the liquid crystal layer 130 is sandwiched between the TFT array substrate 110 and the color filter substrate 120. The LCD panel 100 is divided into a display region 100a and a sealant region 100b. The display region 100a is the part for displaying images. A sealant 140 is disposed in the sealant region 100b for bonding the TFT array substrate 110 and the color filter substrate 120. Generally speaking, the sealant 140 is formed by an ultraviolet curing adhesive, thus, the sealant 140 can only bond and fix the TFT array substrate 110 and the color filter substrate 120 after it is radiated and hardened by an ultraviolet light. If the sealant 140 is not completely hardened, it may contaminate those liquid crystal molecules in contact and may further affect the display quality thereof.
FIG. 1B is vertical view of the LCD panel in FIG. 1A. Referring to FIG. 1B, a plurality of scan lines 112 and data lines 114 perpendicular to each other are disposed on the TFT array substrate 110 of the LCD panel 100 for defining a plurality of pixel regions P arranged as an array in the display region 110a. Each pixel region P contains a pixel structure 116. Each pixel structure 116 includes a TFT 117 and a pixel electrode 118 electrically connected to the TFT 117 for controlling the on/off of the pixel through the TFT 117. Each TFT 117 includes a gate 117a, a source 117b, and a drain 117c. Wherein the gate 117a is electrically connected to the corresponding scan line 112, the source 117b is electrically connected to the corresponding data line 114, and the drain 117c is electrically connected to the pixel electrode 118 via a contact hole. One ends of the scan lines 112 and data lines 114 are extended to the periphery of the sealant region 110b and are respectively connected to a gate driver IC (not shown) and a source driver IC (not shown) so that each pixel can produce grey scale of different color.
However, when the LCD panel 100 has been assembled and put into operation, the light provided by a backlight module (not shown) disposed under the LCD panel 100 passes through the spaces between the scan lines 112 and the spaces between the data lines 114 in the sealant region 110b, and which causes light leakage at the periphery of the LCD panel 100.
To resolve the foregoing problem of light leakage at the periphery of the LCD panel, referring to FIG. 2, a plurality of floating metals 119 are disposed under the sealant 140 for light shielding. However, the floating metals 119 may cause residual charges due to capacitance coupling and which may further cause ESD damage, thus, the quality of the panel may be reduced. Besides, uneven capacitance coupling may reduce the signal consistence of the panel and may cause other parasitic effect.